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ADP2138 Current Limit Details

Reading the ADP2138 datasheet, I see a description of the IC having current limit circuitry, but I would like to know what that circuitry does to limit the current. Does the circuitry shut down the regulator? If not, how does it source the additional current? Because the IC does not have a PGOOD line, I'm wondering what other methods could be used to know whether the circuit could have entered a state where the output is short circuited by the load (aside from sampling and measuring the output with an ADC).

Thanks,

Trevor

  • Trevor,

    as you mentioned since the ADP2138 does not have a Pgood signal the only way to now if you have reached a current limit condition is to monitor the output voltage externally. But even in that condition the output could be only slightly out of regulation if your load does not demand current. The device is not shut down (latched off) if a current limit is reached, there is a cycle by cycle current limit that reduces the duty cycle.

    If the voltage drops below 50% then the switching frequency is reduced.

    So in the case of a real short circuit you would see the switch node (SW) running at a reduced switching frequency.

    If you are interested in a part with Pgood the ADP2120 could work

    Hope this helps.

    AnalogXPRT

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